Throwing wheel vane and method of manufacture thereof



Aug- 1, l957 L.. v. ABRAMS ETAL 3,333,365

THROWING WHEEL VANE AND METHOD OF MANUFACTURE THEREOF Filed oct. 22, 1964 2 Sheetssnee1 1 liyig INVENToRs lOl/is Vflbrms Rdf/'Dh Wlfoore Aug. 1, 1967 v Y 1 v ABRAMS .ETAL 3,333,355

'FHROWING WHEEL VANE AND METHOD OF MANUFACTURE .THEREOF l Filed oct. 22, 1964 zsheetsneep v A j A 104 QUENCHING STA TIoN 'GRIND i STATION Louis Abr/ms @Qcrgok WMOUI'@ L Q ab? SAND CAST r INV'ENToRs United States Patent O 3 333 36s THRoWiNG WHEEL VANE AND METHOD oF MANUEACTURE THEREoF Louis V. Abrams and Ralph W. Moore, Hagerstown, Md.,

3,333,365 Patented Aug. 1, 1967 rapidly and would cause premature breakage by, for example, developing ne cracks.

FIGS. l and 2 illustrate one elective casting technique that produces a plurality of varies 86, 87 from each mold.

5 The above vanes 86, 87 are readily made, for example, ;gnglogogofsgggwggpummm Hagerstown with an ordinary sand casting mold with the gating pro- Filed Oct 22 1964, Sen No. 405,730 vided by a baked sand insert shaped tn provide the de- 9 Claims, (C1. 51 9) sired base bottom configuration. The gating is preferably arranged to have a constriction adjacent the recessed The present invention relates to both e method for 10 lower surface 82 of the Vane so that when the casting is making a vane and a vane for use in a throwing wheel completed and the solidified metal is withdrawn from for projecting streams of particles against Work pieces to the Inold, the gate can be readily broken Oil and Will then Subject the Work pieces t0 cleaning, abrading 0.1- .peening break ClOSe t0 that SlllfaCe. AlhOUgh tll` Vane Call tOleraction -or the like. A typical Wheel of this kind is shown ate a Small amount of gate material Prlolecting out from in U.S. Patent 2,869,289, granted Jan. 201, 1959, and Surface 81, a 1/2 Square inch CPOSS-Setwn gate Will genin U,S Patent 3,151,417 granted 0er 6, 1964 erally break off quite close where the dovetail 85 is fairly Amon-g the objects of the present invention is the promaSSiVe- Particularly goed breaking takes Plaee Where the vision of improved varies for the above Wheels, as well as gate iS made relatiVelY thin, for eXaruPle inch 1u improved methods for making Such venes, width, the desired area being provided by having the gate Other objects and advantages of the present invention extend the necessary length along Surface The Vaues will become more `apparent from a study of the followcan either be east one at a time, 0i' a plurality Cari be Cast ing description and drawings wherein; together by running their respectiveA gates to a common FIG. 1 is a horizontal section of a mold for casting Pour-opening or riSern n the vanes according to the present invention; FIGS- l and 2 ShoW One technique for Produeihg a Plu FIG 2 is a vertiea1 Section of the mo1d of B1G, 1 25 rality of these vanes. A mold is here shown as two varies taken aiong iine 2 2; and 86 and 87 using sand lilling 88 with a baked core insert FIG. 3 is a schematic view of the steps involved in 90 Providing gates 91 runners 92, anti eXP'aIiSion domes producing a vane in accordance with this invention. 93- The Pouring takes Place through riser 94- After east When used in the above type of throwing Whee1s, the ing is Completed varies -86 and 87 are Iremoved from the vanes gradually wear away in view of the eroding action mold and the risers and gates 91 are 'broken olf: h of the abrasive particles, the particles are very hard, such VaiieS 86 and 87 are Preferably of 'abrasioujreslstaut as steel. The movement ofthe particles along and against heat treated alloy Carbon Cqniammg the follwmg C0mthe length of the vane causes erosion of the vane sur- Position bY Percentage of Weight: faces. In some very heavy usages as when sand or alumina Percent contaminate the particles, the varies might have to be C 3 3 replaced after only about twenty hours of operation yor Si 0,46 leSS- cr 16.3 It has been discovered that this wear or erosion starts M0 2 92 at any surface imperfection. For example, even the minute Fe Balance indentations resulting from the Rockwell hardness tests are starts of accelerated wear, although ya magnifying After being cast the varies are then heat treated or glass is necessary to see these minute indentations or imsubjected to a hardening technique lby being treated for pressions. Accordingly by the present invention, throwing about one hour at a temperature lof approximately 1750 wheel varies of improved wear resistance are cast and F. followed by air quenching. surface ground below the depth of the deepest roughness Advantageously, the surface hardness of varies 86 and to provide a vane which is smooth and hat. To further 87 is in the range of from Rc 613 to 68. This hardness resist Wear the vanes may also be tempered in addition range is particularly `desirable because harder faces do t0 being Surface groundnot add to the wear life and are susceptible to cracking Applicants invention is a distinct departure from and chipping, while a face hardness bel-ow Rc 63 reduces prior practices in that heretofore varies were surface the wear life. ground primarily for esthetic reason, to give the vanes The following tables illustrate the Wearability of dry a more pleasant appearance and to dress the shape to the sand cast varies which were treated to 1750 F. and air nal specification. However, there was never any recogquenched. All yof the vanes have the following composition nition that if the varies were actually ground as flat and by percentage weight: smooth as possible, increased wear life would result. Consequently, no conscious effort was made to finish the varies 3.3% C to such Ian extent that they were 'ground below the depth 0.46% Si of the deepest roughness resulting from the casting proc- 16.3% Cr ess, so as to increase the wear life. In fact, it was generally 2.92% Mo believed that yground surfaces would erode much m-ore Balance Fe TABLE I Orig. Wt. at Gram Wt. at Gram Wt. at Gram Gram Vane Type Wt.n End of Loss End of Loss End of Loss Loss Grams 3 Hrs. 4 Hrs. 15 Hrs. Per

Hour

Normal-1 1, 459 1, 455 4 1, 453 6 1, 454 25 1. 67 Normale 1, 456 1, 451 5 1, 450 6 1, 4,24 32 2. 13 Tempered and Ground-1 1, 365 1, 362 3 1, 360 5 1, 336 29 1. 90 Tempered and Ground-2.. 1,364 1,360 4 1, 358 6 1, 328 36 2. 40 Ground-1 1, 382 1, 379 3 1, 377 5 1, 357 25 1. 67 Ground-2 1, 383 1, 380 3 1, 379 4 1, 363 20 1. 33

TABLE II.-SUMMARY OF RESULTS Gram Loss Per Hour Vane Typo At End of At End of At End o 3 I-Irs. 4 Hrs. 15 Hrs.

Normal 1. 5 1. 5 1. 90 Tempered and Ground. 1. 17 1. 38 2. 17 Ground 1.0 1. 13 1. 50

TABLE III Orig. Wt. At Gram Wt. At Gram Gram Vano Type Wt. Hrs. Loss 100 Hrs. Loss Loss Per Hr.

Normal-1 1, 436 1, 413 23 1, 271 165 1. 65 Normal-2---.. 1, 437 1, 412 25 1, 240 197 1. 97 Ground-1 1, 408 1, 388 20 1, 241 167 1. 07 Ground-2- 1, 407 1, 389 18 1, 243 164 1. 64

TABLE IV Gram Loss Per Hour Vane Type At End of 10 Hrs. At End of 100 Hrs.

Normal 2. 29 1. 81 Ground 1. 81 1. 66

As is evident from Tables I and II, although the rate of wear of conventional sand cast vanes is eventually the same as sand cast vanes which are tempered and ground, tempering the vane after grinding does effectively delay the start yof wear. In fact, although not apparent from Tables I and II, at the end of the first hour of testing, the tempered ground face vanes even showed somewhat less wear than the unternpered ground face vanes. Tables I-IV also clearly indicate that the sand cast vanes which are ground smooth and at have an appreciably greater wear life than normal or conventional vanes.

Although ground sand cast vanes are particularly desirable inextending vane life, vanes which are chill cast and surface ground have about a three-to-one longer wear life than the sand cast vanes. The following tables illustrate a comparison of sand cast and chill cast vanes.

TABLE V Vane Type Orig. Wt. Wt. at 10% Gram Wt. at 100 Gram in Grams Hrs. Loss Hrs. Loss Normal Sand Cast No. 1 1, 436 1, 413 23 1, 271 165 Normal Sand Cast o. 2 1, 437 1, 412 25 1, 240 197 Ground Sand Cast No. 1 1, 408 1, 388 20 1, 241 167 Ground Sand Cast No. 2 1, 407 1, 389 18 1, 243 164 Chill .Cast No. 1 1, 422 1, 414 8 1, 359 63 Chill Cast No. 2 1, 405 1, 397 8 1, 343 62 TABLE IV.-SUMMARY OF RESULTS Gram Loss Per Hour The improved results of chill cast vanes over sand cast vanes might be understood from the difference in their microstructures. For example, sand cast and heat treated vanes have a predominance of larger g-rain (Cr, Mo) Fe3C surrounded by tempered martinsitic matrix. The carbides are singular islands, each surrounded by the tough, high strength martinsite which has secondary carbides imparting further hardness within the individual grains and grain boundaries. The micro-structure of chill cast and heat treated vanes, however, has a predominance of line, eX- tremely hard, brittle (Cr, Mo) Fe3C with a martinsitic matrix. The carbides are acicular or needle-like and are coupled in an inter-connected cleavage pattern (dendritic) which indicates a high overall hardness with high brittleness and low overall strength.

Despite the fact that chill cast vanes -give such outstanding results, sand cast vanes are mo-re desirable for large scale use. The main disadvantage with chill cast vanes is the lack of uniformity in production lots. Casting defects predominate the production of the chill cast vanes. Although the best vanes from a large quantity of chill cast vanes would have a wear life three times longer than that of sand cast vanes, the uniformity of production of sand cast vanes makes these vanes more desirable.

FIG. 3 schematically illustrates the method of this invention. As indicated therein after the sand casting step 1016 or the chill casting step 108, the vane is ground at grinding station 110, is then heated at heat station 112, and then quenched at quenching station 114. The resultant vane includes its cast body 102 having a smooth ground abrasive propelling face 104. As indicated above the hardness may advantageously be in the range of from Rc 63 to 68 Rockwell.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. The method of makin-g an abrasive throwing vane having an abrasive propelling face for an abrasive throwing wheel which method consists essentially of the steps of casting a vane, and grinding the surface of said face below the depth of the deepest roughness of said face resulting from said casting step to make said surface smooth and at.

2. The method of claim 1 including the step of hardening said vane after it has been ground.

3. The method of claim 1 wherein said step of casting comprises sand casting said vane.

4. The method of claim 3 including the step of hardening said vane after it has been ground.

5. The method of claim 4 wherein said step of hardening includes heating said vane to approximately 1750 F. and air quenching said vane.

6. The method of claim 1 wherein said step of casting comprises chill casting said vane.

7. The method of claim 6 including the step of hardening said vane after it has been ground.

8. The method of claim` 7 wherein said step of hardening includes heating said vane to approximately l,750 F. and air quenching said vane.

9. A throwing vane having a cast body, an abrasive propelling face on said body, said face having a smooth ground surface, said vane being hardened and having a Rockwell hardness number in the range of from Rc 63 to 68.

References Cited UNITED STATES PATENTS 1,736,495 11/1929 Graff 29-529 2,077,636 4/1937 Minich 51-9 2,134,749 11/1938 Burt 29-529 X 2,204,633 6/1940 Turnbull 51-9 2,314,069 3/ 1943 Blount 51-9 2,376,639 5/1945 Unger 51-9 2,869,289 l/1959 `Gossard 51-9 3,151,417 10/1964 Hartman et al 51-9 LESTER M. SWINGLE, Primary Examiner. 

9. A THROWING VANE HAVING A CAST BODY, AN ABRASIVE PROPELLING FACE ON SAID BODY, SAID FACE HAVING A SMOOTH GROUND SURFACE, SAID VANE BEING HARDENED AND HAVING A ROCKWELL HARDNESS NUMBER IN THE RANGE OF FROM RC 63 TO
 68. 